The present invention relates generally to an improved printing apparatus or composing system, and more particularly, to an improved printing apparatus or composing system of the type involving the use of a pressure process to transfer dry carbon impressions onto an image carrying tape. Such apparatus or system includes a printing station, a printing force generating means, a tape and associated carbon ribbon, a type disc or font element with a raised character positionable in printing alignment with the printing station and means for advancing the tape and ribbon with respect to the printing station. The apparatus of the present invention has particular application in the printing of relatively large characters for use in preparing lettering for engineering drawings, flip charts, overhead transparencies, posters, newspaper headlines, etc. These characters are generally much larger than most typewriters or other conventional means can generate.
In the prior art, several means have been used to create such letters; these include stencils, press-on letters, photographic type setters, thermal type setters and dry lettering printing processes. The present invention relates to improvements in a dry lettering printing process. In such a process, a high pressure is utilized to transfer dry carbon or other ink or color material from a ribbon onto an image carrying tape. A typical process may require pressures as high as 5000-6000 p.s.i. or higher. A type disc or font element having raised portions corresponding to the particular image desired to be printed is commonly used in such a process. Typical prior art machines and apparatus utilizing dry lettering processes are shown and described in U.S. Pat. Nos. 3,834,507, 3,912,064 and 4,015,700 and pending application Ser. No. 726,106, filed Sept. 24, 1976. While most of these prior art machines have been capable of generating generally high quality printing and lettering results, there is a need for a printing apparatus which is simpler in construction (and thus less expensive), requires less maintenance, but which still provides high quality printing and lettering results. Each of the above art patents discloses a printing apparatus having, among other things, a means for generating a printing pressure, and a means for advancing the tape and ribbon through the equipment. The present invention relates to an improved apparatus incorporating an improved means for generating the necessary printing pressure and an improved means for advancing the tape and ribbon with respect to the printing station.